Data Flow Control and Bridging Architecture Enhancing Performance of Removable Data Storage Systems

1. An apparatus comprising a first serial-to-parallel interface that converts serial data signals received from a data storage host controller to parallel data signals; a second serial-to-parallel interface that presents a serial interface to a serial data storage unit; a data flow control circuit operably connected to the first serial-to-parallel interface and the second serial-to-parallel interface, wherein the data flow control circuit is operative to access parallel data storage interface signals from the first and second serial-to-parallel interfaces; a controller unit, operably connected to the data flow control circuit, and the second serial-to-parallel interface, the controller unit comprising a processor; wherein the controller unit is operable to access executable instructions physically stored in a memory and, when executed, operable to cause the processor to: transmit, responsive to a first data transfer command received from the data storage host controller, control signals to the data flow control circuit; and wherein the data flow control circuit, responsive to control signals provided by the controller unit, is further operative to transfer data received from the first serial-to-parallel interface to the second serial-to-parallel interface without intervention by the controller unit.

2. The apparatus of claim 1 wherein the data flow control circuit is operative to patch one or more status signals between the data storage host adapter and the data storage unit.

3. The apparatus of claim 1 wherein the data flow control circuit, responsive to the control signals, directly passes at least one register signal of the first serial-to-parallel interface to at least one register signal of the second serial-to-parallel interface.

4. The apparatus of claim 1 further comprising a command data buffer and wherein the data flow control circuit is operative to route the first data transfer command to the command data buffer for processing by the controller unit.

5. The apparatus of claim 4 wherein the command data buffer comprises one or more first-in-first-out (FIFO) queues.

6. The apparatus of claim 1 wherein the controller unit is further operable to access executable instructions physically stored in a memory and, when executed, operable to cause the processor to access a third data transfer command received from the data storage host adapter; generate a fourth command corresponding to the third data transfer command; and transmit the fourth command to the data storage unit through the second serial-to-parallel interface; receive data from the data storage unit in response to the fourth command; generate a response including the data received from the data storage unit; and transmit the response to the data storage host adapter via the first serial-to-parallel interface.

7. The apparatus of claim 1 further comprising a machine state register indicating status of command execution, wherein the data flow control circuit and the controller unit are responsive to the status indicated by the machine state register.

8. The apparatus of claim 7 wherein the data flow control circuit and the controller unit are both operative to write to, and read, the machine state register.

9. An apparatus comprising a first serial-to-parallel interface that converts serial data signals received from a data storage host controller to parallel data signals; a second serial-to-parallel interface that presents a serial interface to a serial data storage unit; a data flow control circuit operably connected to the first serial-to-parallel interface and the second serial-to-parallel interface, wherein the data flow control circuit is operative to access parallel data storage interface signals from the first and second serial-to-parallel interfaces; a controller unit, operably connected to the data flow control circuit, and the first and second serial-to-parallel interfaces, the controller unit comprising a processor; wherein the controller unit is operable to access executable instructions physically stored in a memory and, when executed, operable to cause the processor to: responsive to a first data transfer command received from the data storage host controller, determine whether to intervene during execution of the first data transfer command; responsive to a determination that the controller unit should not intervene during execution of the command, transmit control signals to the data flow control circuit; and wherein the data flow control circuit, responsive to the control signals provided by the controller unit, is operative to transfer data received from the first serial-to-parallel interface to the second serial-to-parallel interface without intervention by the controller unit.